Simplify the following expression: $9\sqrt{175}$.
Solution: First, try to factor a perfect square out of the radical. $= 9\sqrt{175}$ $= 9\sqrt{25 \cdot 7}$ Separate the radical and simplify. $= 9\sqrt{25} \cdot \sqrt{7}$ $= 9 \cdot 5 \cdot \sqrt{7}$ $= 45\sqrt{7}$